Machine-tool transmission and control mechanism



April 10, 1951 2,548,188

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM J. B. ARMITAGE ETAL 5 Sheets-Sheet 1 Filed Dec. 14 1945 April 10, 1951 J. B. ARMITAGE ET AL 2,548,188

MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM Filed Dec. 14, 1945 5 Sheets-Sheet 2 J/[orney 5 Sheets-Sheet I5 J. B. ARMITAGE ET AL MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM April 10, 1951 Filed Dec.

April 10, 1951 J. B. ARMITAGE ET AL MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM 5 Sheets-Sheet 4 Filed Dec. 14, 1945 e 7 8% w .w hzh. W m n a wJMifl x n3 2 M W 1. 2 1; e wiW H IIIIIIIHH April 10, 1951 J. B. ARMITAGE ET AL MACHINE TOOL TRANSMISSION AND CONTROL MECHANISM 14. 1945 I Filed Dec.

Patented Apr. 10, 1951 UNITED STATES PATENT OFFICE MACHINE-TOOL'TRANSMIS'SION AND I CONTROL MECHANISM" Joseph B. Armitage, wauwatosa andJohn B. Lukey, Kurt A. Riedel, and Francis D; Boehmer, Milwaukee, Wis.,- assignors to; Kearney &

Trecker Corporation, West A1li' Wi m rationofWisconsin ApplicationDecember 14, 1945', SerialiNo.- 635,012

- 7 Claims. 1

This invention. relates generally to improvements in machine tools, and more particularly to an improved automatic boring and milling machine.

selected one of a plurality of feed rates. The. sec and power source also serves to. drive a spindle actuating shaft at one, of. a plurality of speeds. This shaft, in turn, drives. a multiple spindle gear train voperably contained in a, detachable, head mounted on the headstock. The detachable head presents a plurality of, tool. retaining spindles, each positioned to simultaneously efiect a desiredboring or facing, operation upon a. workpiece A general object of the invention is to provide clamped on the table. A rotatable table, built an, improved boring and milling machine of the within; the: machine table, perm-itsv an operation multiple spindle type. to be; performed on any; face orv combination of Another object of the invention is toprovide faces: on. the: workpiece; The power sources for a multiple head milling machine with dog acthe. feed, and spindle; drivesof; the twoheadstocks tuated electrical controls to effect a predeterare electrically'controlled and, interlocked to promined feeding cycle. videi any desired cycle of. feed, and, rapid traverse Another object of the invention is to provide movement. The feed rapidtraversedrives.

. a. slidab'ly mounted milling; machine headstock arecontrolled by'tripidogs adjustably carried on with; a dual drive means to feed the headstock. the headstocks and disposed'to; actuate, switches Another object-is to provide-improved electriacontrol circuit. The; control system. also cal means for controlling the operation of a pluserves to effecta; simultaneous; spindle, speed and rality of motor driven tool elements. feed reduction, at a, selected pointof headstock Another object of the invention is to provide travel, in order tov permit. a facing operation. at a machine having a plurality of spindles to sithevinner endof the boringcut. The-depth. of multaneously perform a multiple boring operatheboringnr facingcut is: determined byfeedtion on a workpiece; a ingthe headstock, against an adjustable-positive Another object of the invention is to provide stop with. a. safety-clutchin the feed transmi sa machine tool having a plurality of headstocks sionserving to. disrupt the; power drive: at the inwith feed control mechanism to operate said stant ofcontact. headstocks simultaneously o individually The foregoing and other objects of. the inventhrough -a preselected feed cycle tion;. which will become apnarent' fromthefollow- Another object of the invention isto provide ing detailed description and. claims, may be an improved electrical control system for a maachieved by meansv of the exemplifying apparatus chine tool including control switches operable depicted; in anddescribed inconnection with. the from trip dogs adjustably positioned. ona movco pa y w rm flh I J able machine element. Figural is: a, general view in: front elevation 4 A further object of the invention is to provide of a. boring; and-milling machine incorporating interchangeable multiple spindle head elements the invention; p 7 for use with a movable machine toolheadstock. i an a ged View ofthe left headstock Another object of the invention isto provide and base. shown in F gt with pa ts b nflw y a screw and nut drive mechanism for a machine 130 S e rapid. v e ive m ha ism in element wherein the screw is driven from one e se de p e. d ed transmission power source and the nut is driven from a drive, mechanism within theheadstock. h 0nd power source. Fig. 3 is a detailedhorizontalview of. part-of According to this invention, an. improved. mi-ll- 40 the feed. transmission, taken on the plane repreing and boring machine is provided, wherein a sentedby the;line.33iin.Eig- ;Q pair of tool retaining headstocks are slidably F g-4 is a e arged' rearv-iew of the. left headmounted in opposed relationship on a base with stock shown in Fig. 2 with the gear train. for the a work retaining table operably mounted on the multiple Spindlesand. the. dog, actuatedelectrical base between the headstocks.v Each of the headcontrols shown; I stocks may be actuated manually or by power i 5 isat a sve se Sect onal view of. the headbymeans of a nut and screw drive. mechanism. stock spindle. driving, and. feeding transmissions, The drive mechanism is driven from two power taken substantially on the. plane'of the line 5-5 sources, one to provide a drive at a rapid traverse in Fig.5- 2. a d rate and the other to provide a feed drive at. a Figs 6iis a, detailed longitudinal, sectional view,.

taken. in a vertical plane along, the line 6+6 in Fig, 5', of the headstock transmission; and Fig fl; is, a. schematic circuit diagramof the electrical control system forrthe spindle drive and feed. motors and: the. rapid traverse motors.

The machine tool shown in the drawings is a boring and milling machine of the dual headstock and multiple spindle type with detachable heads carrying the multiple spindles on the headstocks. Each of the detachable heads is designed for a specialized multiple milling or boring operation, and may be readily changed. The machine, as shown, constitutes a preferred embodiment of the invention, although it should be understood l..t the various features of the invention may be utilized in other machines of different construction, with equal advantage.

Referring more specifically to the drawings, Fig. 1 thereof shows the boring and milling machine, constituting a complete embodiment of the invention described and claimed herein. I Generally, the machine comprises a T-shaped hollow bed or base It), constituting the main frame of the machine. The top side of the stem portion of theT base to supports a slidably mounted table or work retaining member l I. A screw and nut mechanism '(not shown) serves to provide a manually operable means for effecting longitudinal movement of the table, in a well known manner.

The oppositely extending transverse portions of the bed I serve to slidably support a pair of tool headstocks l2 and I3. Thus, the headstock i2 is operably mounted on ways M on the right side of the table II, while the headstock i3 is operably mounted on ways l on the left side of the table II, as seen in Fig. 1. The headstocks l2 and I3 are arranged for power or manual movement on the ways I4 and I5 in a plane normal to the work retaining table II. Detachable tool heads H and i8 aresecured to the headstocks l2 and [3, respectively, in a manner to permit a unified movement of the head and headstock, and to present a plurality of cutter retaining spindles journalled therein toa workpiece fastened on the table II. With the headstocks in axial alignment, boring operations may be simultaneously performed on opposite sides of. the workpiece.

Since thedrive and control mechanism in the two headstocks is identical, only the mechanism in the left headstock I3 is shown and hereinafter described in detail. --Two independently driven transmissions I9 and 20 (see Figs. 2 and 5) are provided for each-headstock. The headstock transmission!!! provides a selective power drive for the multiplespindles and'an independently selective power drive to effect feeding movement of the headstock. The other transmission 29 serves to effect movement of the headstock at rapid traverse rate, and is contained in the machine base in. An electrical control system is vprovided, whereby the four motors associated with the two headstocks l2 and I3 may be controlled 'to drive the tool spindles and effect movement of the headstocks at feed rate or at rapid traverse rate in either direction, independently. Two motors 2i and 22 are connected to drive the transmissions l9 and 20, respectively, for each headstock. Micro-switches mounted on the bed areactuated through engagement with adjustable dogs bolted'on the headstock housing, to provide accurate control of the headstock movement and, consequently, effect a plurality of precision boring operations in a predetermined cycle.

The spindle drive and feed drive motor 2] is carried on an adjustable motor mounting plate 25, pivotally mounted on the top of the headstock, 'a sshown in Figs. 3. and 5.. The motor 2| drives a pulley 26 through a plurality of V-be1ts'21, the

4 tension of the belts being adjusted through the adjustment of the motor mounting plate 25. The pulley 26 is keyed on the outer end of a shaft 28, journalled in the headstock, as shown in Fig. 2. A worm 29, integrally formed on the inner end of the shaft 28, meshes with and drives a worm wheel 30 (see Figs. 2 and 6). The wheel 30, in turn, is fixedly carried on a shaft 3|, journalled transversely of the headstock. A bevel or pinion gear 32, keyed to the shaft 3 l, is disposed between a pair of reversing bevel gears 33, as shown in Fig. 5'. The reversing gears are rotatably carried on a shaft 34 with a shiftable clutch collar disposed between them for selective engagement, to provide a drive to the shaft 34 in either direction. A knob 35, on the front side of the headstock,

' may be selectively positioned to shift the reversing clutch, in a well known manner.

A plurality of shiftable gears, constituting a gear train 33, are driven from the shaft 34 and are disposed within the headstock for axial movement in such a manner that they may be shifted to provide a plurality of speed drives to a spindle driving take-off shaft 39. A spindle speed selector ifl, operably mounted on the front of the headstock, serves to shift the various gears in the gear train 38, in a well known manner, to provide the selected spindle speed, as indicated by the dial 4!. The shaft 39 is journalled within the headstock with an internally splined socket G2 exposed on the inner end face of the headstock, as shown in Fig. 4. The detachable head is, mounted on the front end of the headstock, is provided with a shaft 43, having an extending splinedend 44, disposed to fit within the socket t? when the head is properly positioned and clamped on the headstock. A plurality of cutter retaining spindles are journalled within the head l8 and are driven from the shaft 43 through interconnecting gear trains.

In order to provide a positive relationship between the rate of rotation of the spindles 45 and the feed rate of headstock movement for thread cutting or the like, the power source for the headstock feed transmission is taken directly from the spindle driving take-01f shaft 39. As shown in Figs. 5 and 6, a bevel gear 48 is keyed to the inner end of the shaft 39 and meshes with a mating bevel gear 49. This gear, in turn, drives a shaft 50 which carries, at its other end, a gear 5| disposed between, and meshing with, a pair of reversing gears rotatably journalled on a shaft 53. A clutch collar 54, slidably splined on the shaft 53, between the reversing gears 52, may be selectively positioned to engage either one of the two gears to provide a driving connection to the shaft 53 in either direction. The clutch collar 54 may be selectively positioned, through the manipulation of a feed reverse handle 55, to either one of two positions. Thefeedreversin mechanism is provided in order to permit a forward or reverse feed movement of the headstock in relation to the clockwise or counterclockwise rotation of the spindle shaft 39, as maybe required for a particular machining operation. A plurality of gears, constituting a feed gear train 58, are driven from the shaft 53. Certain of the gear clusters in the gear train are axially shiftable to selectively provide a plurality of feed rate drives to a shaft 59. The gear train 58 is carried in a feed box frame 60, which is detachably mounted on the back side of the headstock. Thus, the entire unit may be readily removed from the headstock for servicing. A feed selector mechanism 6|, also carried in the feed box sheet sired feed rate, as indicated on a dial 62. A bevel gear 54, keyed to the shaft 59, meshes with a bevel gear 65, keyed to the upper end of a vertically disposed shaft 68, journalled within the headstock, as shown in Figs. 4 and 5. At the lower end of the shaft 66, a bevel gear 67 meshes with a ring gear 63, constituting. the driving member of an overload clutch mechanism 59, as best shown in Fig. 3. A driven member ll} of the clutch mechanism is keyed to a' horizontally disposed shaft li, journalled within the headstock,

as shown in Figs. 2, 3 and 4. Likewise keyed to the shaft 'H is a gear 15, which meshes selectively with and drives agear l6, fitted on a splined shaft ii. The gear H5 is axially slidable on the shaft il to either a position of engagement with the gear 75 or a neutral or disengaged position. The hub of the gear 76 is providedwith a groove 78, which receives a shifter fork 75. The fork 79 is manually operable through a lever 89 operably mounted on the front side of the headstock. The lever 89 may be positioned in an engaging position, in which the gear 16 is engaged with the gear I5 to provide a power drive to a worm 83, integrally formed with the spline shaft 17, or in a disengaged position in which the feed drive to the shaft T. is disconnected. The worm 83 drives a worm wheel 86, integrally formed on the outer periphery of a nut element 85 journalled in bearings 86 on the bottom side of the headstock,

as shown in Fig. 2. The nut $5 threadably engages a feed screw 8?, which is operably journalled parallel with and between the way surfaces [5 in the bed 18. When the worm wheel 84 is driven at a preselected feed rate, the driving engagement between the nut 85 and the screw 81 will effect longitudinal movement of the head stock [3 on the horizontally disposed ways 55 in either direction. Thus, the headstock l3 may be operated at a predetermined feed rate, relative to the speed rate of the cutter spindles it.

The headstock is may also be driven at a rapid traverse rate, in order to rapidly advance the cutters toward the workpiece or tdwithdraw the cutters, after an operation is finished. The rapid traverse transmission 29, as shown. in Figs. 2 and 4, is disposed in the outer end'ef the base In, intermediate the ways. I5. The transmission is driven by the motor 22, mounted on the back side of the base [0. The extending end of a motor shaft 90 is splined to receive a worm 9!, journalled within the base Iii. The motor 22 may be readily removed from the machine, without disturbing the rapid traverse transmission 28. The worm 9i engagesaworm wheel 92, keyed on 'a shaft 93, as shown in Fig. 2 The shaft fifii is journalled in a transmission casing Bli bolted to the bed is, intermediate-.the-ways l5. A. spur gear 95, likewise keyed to the shaft 93 adi ent to the worm wheel 92, meshes with a gear. 96, fixedly carried on the end of the screw shaft 81.

' The screw shaft 8'! is j'ournalled in bearings 91 and 98, mounted in the rapid traverse transmission casing 96. Since the rapid traverse motor 22 is designed to operate at a constant speed, the

screw shaft operates to move the headstockat a predetermined rapid traverse rate.

When the rapid traverse motor is. energized to .drive the transmission 20 and, consequently, the

screw shaft 87 at a rapid traverse rate in "either" direction, the nut element 85 is not actively driven and the rotative force from the screw will be imparted to the nut to effect movement of the headstock. Since the nut element 85 is driven directly from the worm 83 and the worm wheel 84, the rotative force imparted to the nut will not cause it to turn with the screw, but rather the worm 83 will serve to lock the wheel 84 and nut 85 against rotation.

However, when the headstock is moved at feed rate, the nut 85 is driven from the headstock transmission to rotate on the screw shaft 81,

and the screw shaft is prevented from turningby the self-locking worm 9| and worm wheel 92. Furthermore, the electrical controls for the machineare then set to energize an electrical brake built into the rapid traverse motor 22 and lock the motor 22=and the screw shaft B'lto which it is connected against rotation. Thus,

the headstock willbe moved along the way surfaces at a selected feed rate. Since each of the drives is independently driven and geared, it is possible that both could be operating simultaneously, without causing any damage, although the electrical control circuit, as will be hereinafter fully described, will obviate such a possibility during a normal operating cycle.

A positive stop device lfll is mounted on the base intermediate the way surfaces l5, as shown in Fig. 4. The device llll is adjustably mounted and is provided with a micrometer dial H12 in a manner to permit an exact adjustment of the stop in a well known manner. The stop serves to engage an extending arm portion I03 integrally cast with the headstock casing, whenever the headstock is advanced to a preselected foremost position; Thus, at the completion of a boring or facing operation, the headstock will be fed against the positive stop device [BI and effect a cutting operation to a known distance. When the feed movement of the headstock is disrupted through the abutment of the arm portion [03 against the positive stop device, the overload clutch 69 will serve to interrupt the feed drive to the nut element 85, without straining any of the driving elements in the transmission 19.

When the machine is being set up for a particular milling or boring operation, the headstocks may be manually fed along the way surfaces. As shown in Fig. 1, an extending portion I04 of the nut rotating shaft 11 on the front side of the headstock is adapted to receive a crank N15. The shaft IM is provided with an adjustable micrometer dial to permit precise adjustments of the headstock along the way surstocks of this machine are effected entirely through electrical control elements interconnected to constitute an automatic electrical control system. Although the machine, as shown, includes two electrically controlled headstocks. a machine'incorporating the principles of this invention can be built with a single headstock or several pairs of headstocks disposed along a power driven table having an automatic control cycle synchronized with the operating cycles of the headstocks. Generally, the cycle of a boring operation includes the advancement of the cutters to the workpiece at a rapid traverse rate and then a feeding movement at a desired feed rate while the cutter is operating on the workpiece. If a facing operation is necessary at the end of .the bore, the controls may be predeterminately set to reduce the cutter speed and feed rate during such an operation. When the cut is completed, the headstock is moved at rapid traverse rate, back to its outermost position. If the areas to be cut in the workpiece are spaced, the controls may be adjusted to advance the cutters automatically from one such area to the next, at rapid traverse rate.

The electrical circuit required to accomplish the automatic control of a single headstock is diagrammatically shown in Fig. '7. The circuit for each additional headstock is identical, the several circuits being interconnected through the master switches, as hereinafter fully explained. Electrical energy for the headstock motors 2| and the rapid traverse motors 22 and for the other electrical equipment in the circuit is derived from a power source indicated by the line conductors L L and L in the circuit diagram. A master switch I20, connected to the line conductors, serves to control all current flowing into the circuit. V 7 -As shown in Figs. 1 and 4%, each headstock is operated from a control station I2I or I22 lo: .cated, respectively,-on opposite sides of the extending portion of the bed III, immediately adjacent thetable II. These positions afford the greatest accessibility to the operator, while setting up the machine or during the cutting operations. In addition, multiple operation of the headstocks may be eiiected from any of the corresponding control stations similarly positioned for each of the other headstocks.

In the circuit diagram (Fig. '7), the manually operated switches in the top row are mounted in control station I21, while the switches in the bottom row are mounted in control station I22.

As a preliminary to operating the headstock motors 2| it is necessary to'energize a control circuit. This circuit may be controlled from a dual start button I23 or dual stop button I24, mounted in each of the control stations on the machine. In addition, this circuit may be controlled from a head start button I25 and a head stop button I26, but only from the two control stations directly associated with the headstock, which is to be operated. Thus, the dual startstop switch buttons I23 and I24, at any of the control stations on the machine, may be actuated to effect multiple operation of all of the headstocks while the head start-stop buttons I25 and I26 each serve to effect operation of a single headstock.

If the control circuit is to be energized by actuating either of the dual normally open start buttons I23 at the front or rear control stations I2I or I22, a current flow originating from the line conductor L would be established through a line I29 to a normally closed interlocking switch I30 in a reversing drum I3I. Thence, through a line I32 to the dual stop switch I24 at the control ,station I2I, the normally closed switch and a line I33 serially connecting the switch with the dual stop switch at the control station I22. Thereafter, a line I34 conducts the current to one terminal on each of the two normally open dual start switches I23 in the stations I2I and I22, respectively. The momentary closing of one of the dual start switches will permit a current flow through the switch and a line I35 to an operating solenoid I36 of a control relay I31. The solenoid is connected to the line conductor L by a line I38, and when thus energized, the relay will be actuated to a closed position. When either of the dual start buttons is depressed, a

circuit is also established from the line I34 to a line I40, which connects with a solenoid in each or the other control relays I (not shown) identical to the control relay I31 and associated with simi lar control circuits for each of the other headstocks. Consequently, the depression of any of the dual start buttons, at any one of a plurality of headstock stations, will cause each of the headstock control relays to be energized and closed.

If, on the other hand, only one headstock control circuit is to be utilized, the operator can energize the control relay I31 by actuating one of the headstock start switches I25 at either the front or rear control station for the particular headstock. Thus, in the instant case, in order to energize the relay I31 in the left headstock control circuit, as shown in Fig. '7, the actuation of one of the switches I25 would cause a current flow from the lin L through the dual stop switches I24 and the line I34, as previously ex plained, to a line MI and a pair of normally closed head stop switches I26 connected in series by a conductor I42. Thereafter, the current will flow to each of the head start switches 225, via a line I43 and through the closed switch to the line I35 connecting with the solenoid coil I36 in the control relay I31 to efiect mechanical movement of the relay to a closed position. Since the dual start switches I23 remain open, the line I40 to the other headstocks is not energized.

The closure of the relay I31 establishes a holding circuit to retain the relay in a closed position, until such time as the current flow to the solenoid coil I36 is disrupted to effect an opening of the relay. The establishment of the holding circuit by the closure of a contact plate I44 in the control relay I31 permits a current flow from the line conductor L to the dual stop switches I24, the lines I34 and I4I, the serially connected head stop switches I25, and the line I43, as previously explained, then through a line I45. a normally closed dog actuated limit switch I46 and a line I41, connecting with one terminal associated with the plate I44. Since the other terminal is connected to the line I35, the how to the control relay solenoid I36 will continue in shunt relationship with the starting switches I25, to eiiect the retention of the relay I3! in a closed position.

The energization of the control circuit up to the aforedescribed stage, must occur, in each instance, before any cycle of machine operation can be initiated. However, the further operation of the control circuit is dependent upon the selective manipulation of various switches at the control stations and upon the operation of a series of limit switches predeterminately set to function in a desired sequence. Six limit switches I46, I48, I49,'I50, I5I and I52, as shown in Fig. 4, are mounted along the top rear edge of the extending portion of the bed Ill. Each switch is operably disposed to be actuated through engagement with one of the adjustably mounted trip dogs or actuators I53 to I58 (see Figs. 4 and 5). The trip dogs are adjustably retained in position on the movable headstock through a T-bolt and nut I59, slidably retained in a T-slot I60 in a well known manner. Thus, the positioning of each of the trip dogs, to effect the manipulation of its associated limit switches, provides for actuating the several switches in a predetermined sequence during the cycle of headstock movements, to complete or open various circuits, as will hereinafter be more fully explained.

Thus, for example, the first movement of the headstock is generally at rapid traverse rate, in order to advance. the cutters into the proximity of a workpiece on the table I I and start a cutting operation. The closure of the control relay I31 permits a current flow from the line conductor L through a line I6I and an engaged control relay plate I62 to the conductor I63. This conductor, in turn, connects with a movable plate I64, in a timing relay switch I65. Normally, the plate I 64 is positioned to permit a current flow to a line I66, which connects with the double-pole, single-throw limit switch I48, known as the feed limit switch. When the headstock. I3 is advancing, the switch I48 is positioned, as shown in Fig. '1, to permit a flow to the normally closed limit switch I49 and a conductor I68. This conductor is connected to permit a current flow across a contact plate I69, associated with an inching relay I10, the plate I69 being retained in a closed position as long as the relay I18 remains deenergized. From the plate I69, the current is directed to a line I1I connected to an actuating solenoid I12 which, when energized, closes a forward rapid traverse motor switch I13 that functions to energize the rapid traverse motor 22 from the line conductors L L and L and thus effect forward rapid traverse movement of the headstock.

The circuit is completed from the solenoid I12 through a line I15 connecting with a safety interlock I16 in a reverse rapid traverse motor switch I11. The interlock I16 permits a passage of current only when the switch I11 is deenergized. Whenever the switch I 11 is energized to effect a reverse movement of the headstock, the circuit to the forward solenoid I12 is broken. Thus, it is impossible to close the forward and reverse motor switches I13 and I11 simultaneously or to close one when the other is already closed. Thereafter, the current is directed through a line I18 to a pair of serially connected overload relays I19 and I80, operably connected in the rapid traverse motor circuit. These relays serve to open the control circuit to the motor switches I13 and I11 whenever an overload occurs on the rapid traverse motor 22. The circuit i completed through a common return line I8I connecting with the relay I88, which in turn, connects with the line I38 and the conductor L via a contact plate I82 in the control relay I31. It is evident that the circuit is broken whenever the control relay I31 is in an open position, since the contact plates I82 and I82 are displaced to interrupt the flow of current.

The headstock will continue to be rapid traversed forwardly until either one of the limit switches I 38 or I49 is actuated by its associated predeterminately set trip dog I53 or I54, respectively, carried on the headstock. Thus, if the limit switch I49 is actuated by the dog I54, the circuit is disrupted and forward movement of the headstock at rapid traverse rate will be halted. Since such an actuation of the switch I49 does not complete another circuit, further operation of the machine is dependent upon the manipulation of one of the start buttons at one of the control stations I AI and I22. However, in the arrangement of dogs shown in Fig. 4, the dog I54 is positioned out of the range of the switch I49 and, consequently, never strikes it.

Directly connected to the rapid traverse motor 2| is an electric brake I14 designed to be operable whenever it is deenergized. It is energized from the rapid traverse motor conductors, as shown'in Fig. '7. Thus, whenever the rapid traverse motor is energized to drive the headstock I3 in either direction, the brake is off .and the was feed screw 81 is free to be rotatively driven. But when the motor ZI is deenergized, the brake is set to lock the screw 81 and hold it stationary, to permit the nut element 85 to be rotatively driven on the screw and provide feed movement of the headstock, at a preselected feed rate. The brake I 14 is instantaneous in responding and, consequently, prevents over-travel of the headstock after the limit switch is opened.

To provide a continuous operating cycle for the machine, the trip dog I53 actuating the feed limit switch. I48 may be predeterminately adjusted to actuate the switch from the position shown in Fig. '7 to break the circuit to the forward motor switch I13 and, consequently, to de: energize the rapid traverse motor 22. The switch 148 is of the double-pole, single-throw type and when it is so actuated by the dog I53 on the forward pass of the headstock, a second circuit is completed through it from the line I66 to a line I85 connected to one of a pair of terminals associated with a normally closed contact plate I86 in the inching relay I19. The position of the plate determines the current flow to a line I81, which is connected to a movable contact plate I88 in a spindle motor timing relay switch I89. Normally, the plate I 88 is positioned. to conduct current to a line I98 and the double? throw, single-pole limit switch I581 .The positioning of the switch I59 determines the speed at which the motor 2I is to operate. of an operating cycle, the switch I 59 is positioned, as shown in Fig. 7, to energize the motor 2i for high speed operation, while the cutters are to be used for boring purposes. When thuspositioned, current flows from the plate I88 in the timing relay I99 to the limit switch I56, as previously explained, and thereafter, via a conductor I to a solenoid coil I99 disposed, when energized, to connect the motor 2! to the line conductors L L and I. for operation at high speed upon actuation of a high-speed motor starting switch I91. If a facing operation is necessary at the end of the bore on the workpiece, a trip dog I55 is set to trip the limit switch I59 to open the circuit to the high-speed switch I91 and to close a circuit to a low-speed motor starting switch I98, by permitting a current flow through a line I99 to an actuating solenoid 280. The speed control switch I58 will operate in this manner only upon a forward pass of the dog I55 mounted on the headstock.

The spindle and feed drive motor 2! is preferably of a two speed constant torque, single winding type. When the high-speed motor switch I91 is closed through energization of the solenoid I96, the motor 2! is energized to run at a high speed and the cutter spindles and headstock feed drive mechanism driven thereby will operate at the speed and feed rates as selectively indicated on the spindle speed selector and feed selector dials II and 62. But, when the low-speed motor switch I88 is closed, the windings in the motor 2| are energized in a manner to eiTect a power drive at a reduced speed. In the particular case, the speed is reduced to onehalf and, consequently, the spindle speed and headstock feed rate is reduced accordingly. Whenever the high speed motor switch I9? is closed, an auxiliary contact plate 29I therein closes and shorts out the low-speed motor circuit on the motor side of the switch I98, which is then open. In addition, the usual interlocking means (not shown) is providedfor the motor switches I91 and I98, to prevent the possibility At thestart of having both switches closed at the same time.

The previously mentioned reversing drum I3| is manually operable to change the phase setting of the line conductors L L and L and, consequently, serves to selectively effect reversal of the motor 2|, as may be required for a particular cutting operation. The reversal thus effected in both the high and low speed range is used primarily to control the direction of rotation of the cutter spindles, with the direction of headstock feed movement being controlled mechanically by the manipulation of the feed reverse handle 55, as previously explained. Since the electrical interlock I30 in the drum I3I is serially connected with all of the stop switches in the control panels |2I and I22 and is ar ranged to be opened upon movement of the drum, any change in the setting of the reversing drum will result in opening the holding circuit for the control relay I31 and, consequently, will instantly deenergize all of the motors in the same manner as if any of the stop switches were depressed.

The circuit from the two actuating solenoids I96 and 260 in the motor switches I91 and I98 is completed through a connecting line 262 which, in turn, is connected to one of four serially con nected overload relays 205, 206, 281 and 268, electrically disposed in the high and low speed motor circuits, in a well known manner, to efiectively break the circuit to the motor switch solenoids I96 and 20!! upon the occurrence of an overload and thus disconnect the motor 2| from the line conductor-s L L and L Thereafter, the circuit extends through the common return line |8| and the contact plate I82 in the closed control relay 131 to the line I38 and the conductor L The duration of any cutting operation may be electrically controlled by the two timing relays I65 and I89. The depth of a bore or the limits of a facing operation on a workpiece are pre cisely determined by feeding the headstock I3 against a predeterminately set positive stop device IIlI adjustably mounted in the bed I0, as previously described. Thus, while the forward movement of the headstock will be halted, the headstock motor 2| will continue to drive the cutter spindles for a predetermined period of time under control of the timing relays, even though the headstock I3 may already be moving rearwardly, as effected by the energization of the rapid traverse motor 22 in reverse. In this manner, the workpiece may be precision cut to a predetermined depth, but the usual cutter marks and scratches resulting from withdrawing a nonrotating cutter from a work-piece are eliminated.

After the motor 2| has been energized to rotate the cutters and effect movement of the headstock 3 at feed rate in a cutting operation, a predeterminately set trip dog I56 will actuate the normally open limit switch to close a timing relay circuit whereby both of the relays I65 and I89 are energized. Means (not shown) are provided in each relay to selectively vary the time factor in which the relay will function, after it is energized. When the limit switch I5| is closed, a flow of current is set up from the conductor L the line H, the contact plate I62 of the control relay I31 and the line I63 through the switch |5| to a timing switch supply line 2H1. This line connects with actuating solenoids 2H and 2I2 in the timing relays I65 and I89, respectively. The circuit from the solenoids is completed through the common return line 12 I8|, the contact plate I82 in the contact relay I31 and the line I38 to the line conductor L The operation of the timing relay sets up a holding circuit whereby current is fed directly from the line I63 through contact plates 2I3 and 2M in the timing relays I55 and I89, respectively, and the line 2) connecting with each of the timing solenoids 2H and 2|2 in shunt relationship with the limit switch |5I The circuit from the two solenoids is completed through the common return line I8I, as before. The operation of timing relay I89 serves to actuate the plate I88 from the position shown in Fig. '7, and, consequently, serves to interrupt the circuit to the limit switch I50 and the spindle and feed headstock motor 2|. When this occurs, the motor 2| is deenergized to stop further rotation of the cutters and movement of the headstock.

Actuation of the timing relay I to a closed position serves to effectively move the contact plate I64 from the position shown in Fig. '1 into contact with a terminal 2I5. Such movement serves to interrupt the circuit from the supply line I63 to the line I66 and the limit switch I48. Thus, it would not be possible to effect closure of the forward rapid traverse motor starting switch I13 or to energize either of the headstock motor starting switches I91 and I98 to operate the motors 2| and 22, as aforedescribed.

The timing relay I65 is brought into operation when a machining cycle requires that the cutter be withdrawn from contact with a workpiece while the cutter is rotating. By adjusting the timing element in the relay I65, the time interval during which forward rapid traverse, or forward or reverse feed movements of the headstock occur may be positively controlled.

The movement of the timing relay contact plate I64 into engagement with the terminal 2I5 directs a current flow from the line N53 to a line 2|6, which connects with one of a pair of serially connected hand or automatic selection switches ZIS and 2|9. These switches serve to provide for automatic cycle control of the rapid traverse return movement of the headstock. If either is set for hand control, the circuit is interrupted and the return movement must be initiated each time by the manipulation of other switches, herein after described. With the switches in the closed automatic position, as shown in Fig. '1, the current is free to flow from the switches to a line 220, which is connected to a normally closed limit switch I52. With the presently described machining operation, the switch I52 is not used for control purposes. How- 'ever, it serves to break a circuit to the reverse rapid traverse switch I11, when it is necessary to halt the rearward movement of the headstock I3 at rapid traverse rate, in order to rovide for a feed movement of the headstock during the return portion of the operating cycle. Thus, with the tripping setup shown in Fig. 4, the trip dog I51, which would be used to actuate this switch is positioned out of the operating range of the limit switch.

After passing through the switch I52, the current is carried via a conductor 22| and a normally closed contact plate 222 in the inching relay I1|l to a line 223, which in turn connects with an actuating solenoid 224 in the reverse rapid traverse motor switch I11. From the solenoid 224, the current is directed to an interlock 225 in the forward rapid traverse motor switch I13 through a line 226. When the forward switch 113 is in open c ance position, theinterlock 225 is positioned to permit the passage of current to a line 21, whichconnects-with theline I113. The interlocks I and 225 in the motor switches 111 and I13, respectively, serve as an electrical safety device to prevent the closure of either motor switch when the other is already closed As previously described, the circuit from the motor switches I13 and I11 is completed through the line I 18, the overload relays I19 and I 80, the com mon return line I8I, thecontact plate I82 inthe control relay I31 and the line I38 to the line conductor L When the reverse motor switch I11 is closed,

the rapid traverse motor 22 is energized to efiect rearward movement of the headstock assembly I3 at rapid traverse rate. A holding circuit is set up upon the closure of the motor switch I11 whereby current is directed from the supply line I63 to a line 229, which connects with a holding interlock 230 in the motor switch I11. With the interlock 230 in a closed position, the circuit extends through the line 220, the limit switch I52, the line 22I, the inching relay contact plate 222 and the line 223 to the actuating solenoid 224 of the reverse" motor switch. Thus, the solenoid 224 continues to be energized and the'motor switch I11 is retained in a closed position. The rapid traverse motor 22 continues to drive the headstock rearwardly until the fixed dog I58 (see Fig. 4) actuates the limit switch I46. Thus, the normally closed switch I46 is opened to break the holding circuit to the control relay I31 and disconnect both motors from the line conductorsv During the rearward movement L L and L of the headstock at either feed or rapid traverse rate, the trip dogs I53 and I55 reactuate the limit switches I48 and I50, respectively, in order toreset the switches for the next operatingcycle. The other limit switches I46, I49, I51 and I52 automatically return to their normal position after the associated trip dog has passed and, consequently, do not need resetting.

Briefly reviewing the cycle just described, the

control circuit is energized when the operator actuates either of the dual starting switches I23 or the head starting switches I at either of the control stations I2I and I22 to energize and close the control relay I31. The closure of the relay I31 establishes a circuit fromthe line conductor L through the relay contacts and a timing relay I65 to a pair of limit switches I48 and. I49. With the switches positioned as shown in Fig, 7,

a circuit is established to energize the forward rapid traverse relay I12 and effect a forward movement of the headstock at rapid traverse rates. Such movement will continue until a trip dog I54 operates the switch I49 to halt all forward movement, or until a trip dog I53 strikes the switch I48 to redirect the current through the inching relay I10, the timing relay I 80 and the limit switch I to one of the starting switches I91 and I98, associated with the spindle motor 2|. dependent upon the position of the reversing drum I3I while the rate of rotation-is dependent upon the positioning of the limit switch I50. For boring operations, the switch I50 is positioned to energize a high speed circuit, while for facing operations the switch I50 is tripped by a dog I55 to energize a slow speed motor circuit.

The cycle of headstock operation is automatically continued when the headstock has reached a predetermined forward position whereat a trip The direction of rotation of this motor is dog .I50-will actuate the limit switchIEI to err-- ergize both of the timing relays I and I89. If the relay I89 is set to control the cycle, the spindle feed motor 2| will continue to-sb'e en ergized for a predetermined period of time and then be disconnected from the line to complete the cycle. Whereas, if the relay I65 is set to control the cycle, the motor ill will continue to be energized for a predetermined period of time, after which the relay I65 will function to en'- ergize a reverse rapid traverse motor switch I11 to start the motor 22 and efiect rearward movement of the headstock at rapid traverse rate. Rearward movement of a headstock may be stopped at any point, if the trip dog I51 is set to operate the limit switch I52 and such movement is positively stopped when the fixed dog I58 actuates the limit switch I46 to open the control relay I31 and complete the cycle of operation.

The aforedescribed cycle of operation is only one of several which can be set up on this machine. By predeterminately setting the trip dogs on each of the machine headstocks, a fully automatic operating cycle can be established for each headstock. Any combination of feed and rapid traverse headstock movements can be effected for either forward or rearward travel. In addition, several control combination may be introduced for either boring or facing operations. A similar power feed and rapid traverse drive mechanism may be applied to eiiect precisely controlled movement of the table Or Work retaining member :I I to permit a "sequential series of operations along transverse paths or on each of a'plurality of workpieces.

In order to facilitate setting up the machine for a desired cutting operation, an additional setup control circuit is provided to assist the machine operator in making various adjustments and changes in the control cycle, such as precisely adjusting the trip dogs I53'to I 58, inclusive. By positioning either one of two runinch switches 234 and 235 from the position shown in Fig. '1, into an inch position to permit current flow from a line 235 to a line 231, an energizing circuit is set up for the inching relay I10. Thus, with the control relay I31 closed, a current will pass from the line conductor L the line ISI, and the control relay contact I02 to the line 1 63 and a1ine238 connecting with an actuating solenoid 239 in the inchin relay I10. Thence, through the line 236, the closed run-inch switch and aims 231 joining with the common return line IBE. Thereafter, the current flows through the closed control relay plate I82 and retained in a closed position. Thus, with the plate 240 closed, current is free to flow from the control relay I31 and the lines I03 and 238 through the plate 240 to a Wire .2243 connecting with'the head start switches in the control stations I2I and I22. When either of. {these switches is manually depressed, the current :will

flow through a line 244., which connects with and conducts'current to the line I?! I and the actuat mg solenoid I12 in the forward rapid traverse motor switch I13. Since a holding circuit is not provided, the rapid traverse motor 22 will be energized to efiect forward movement of the headstock I3 at rapid traverse rate only as long as one of the head start switches I remains depressed.

In addition, with the inching relay III) and the control relay I31 both closed, a circuit is established from the conductor L through the lines- IIiI, I63 and 238 to the inching relay contact plate MI and through a line 241, which connects with a pair of head return switches 248 and 249, disposed in the control stations I2l and I22. When either of the push button switches 248 or 249 are depressed, current will flow from the line 241 through the switch to a line 250, which connects with the line 223. With the contact plate 222 in the relay IIll, then open, the current flow will be directed via the line 223to energize the solenoid 224 in the reverse motor starting switch III. The rapid traverse motor 22 will be connected to the supply lines L L- and L to start the motor and efiect movement of the headstock I3 rearwardly until the operator releases the depressed head return switch. Manual operation of the switch is necessary in order that the machine operator may caus the headstock I3 to move rearwardly, as selected, for short distances while setting up the machine for an operating cycle.

To complete an operating cycle, the head return switches 248 and 249 may be manipulated to selectively effect rearward movement of the headstock I3 at rapid traverse rate. For example, if a facing operation is required during the return movement of the headstock, the operator adjusts the operating cycle to halt all rearward movement of the headstock upon completion of the facing operation, in order to provide for removing the cutter from the spindle 45. For such an operation, one of the previously mentioned hand automatic switches 2I8 or 219 is positioned to open the circuit from the line 2 I6 to the line 225 and prevent the automatic energization of the rapid traverse motor 22 for rearward headstock movement. Thereafter, in order to effect such movement of the headstock, the operator actuates one of the head return switches 248 or 249. the contact plate I64 of the closed timing relay I65 would flow from the line 2I6 through one of the switches 248 or 249 to a line 253. This line,

in turn, connects with the line 22 I, through which the current flows to the inching relay contact plate 222 and the line 223. The solenoid 224 in the reverse rapid traverse motor switch is thus energized from the line 223 to effect energization of the rapid traverse motor 22 for reverse movement of the headstock.

Thereafter, the holding circuit, as previously explained, becomes effective to retain the reverse motor switch IT! in a closed position. The rapid'traverse motor 22 continues to drive the headstock rearwardly until either of the limit switches I46 and I52 is actuated by a trip dog or one of the stop switches I24 and I26 is manipulated by the operator.

When the inching relay III] is retained in a closed position through the closure of either of the run-inch switches 234 and 235, as previously explained, the contact plate 242 in the relay is also closed to permit selective controloi the motor 2I to inch the cutter retaining spindles 45. With the control relay I31 closed, a current flow Thus, the current passing through vention and discovery:

fromi'the onductor. L is estabhshed'totwo spindle inch switches 254 and 255 in the control stations l2I and I22 via the line Ifil, the closed control relay contact I62, the line I63 and 238 and a line 255 connected to the inching switches. Any actuation of either of the inching switches 254 or 255 permits a current flow through a line 25? connecting with the closed contact plate 242 in the inching relay H8. The current will then flow through a line 258 and the line I98 to the limit switch I553. Depending upon the position of the limit switch I55, the current will be directed through the lines I or I59 to the actuating solenoids I96 or 260 of the spindle motor starting switches I91 and I98, respectively. No matter which switch is operatively closed to connect themotor 2I to the conductors L L and L the motor will be energized to drive the-transmission I9 and the spindles 45 for inching purposes.

From the foregoing description and explanation of the operation of the milling machine herein set forth to exemplify the invention, it should be apparent that .a new and improved machine tool especially adapted to high speed production milling and boring operations has been provided wherein the sequence of operation is electrically controlled with a high degree of accuracy.

Although the illustrative embodiment of the invention has been described in considerable detail for the purpose of setting forth an operative and -practical exemplifying structure, it is to be understood that the various structure and elec-, trical control systems herein described are illustrative only and that various characteristics of the invention may be incorporated in other struc-. tural iormswithout departing from the spirit and scope of the invention, as described in the subjoined claims.

The principles of the invention having now been fully explained in connection with the foregoing description of an illustrative preferred embodying structure, we hereby claim as our in- 1. In a machine tool, a base, a work support carried by said base; a tool support movably mounted on said base in cooperating relationship with said work support, a tool spindle rotatably mounted in said tool support, a motor carried by said tool support and operatively connected to rotate said spindle, a driving nut rotatably mounted in said tool support, an irreversible drive mechanism operatively connecting said motor to said nut to drive it for advancing'said tool support in synchronism with rotation of said spindle, a feed screw rotatably mounted in said base and having threaded relationship with said nut in' said tool, support, a motor mounted in said base for driving said screw to effect movement of said tool support at rapid traverse rate, and an irreversible drive mechanism operatively connecting said motor tosaid screw, the arrangement being such that either said nut or said screw may be driven to efiect movement of said tool support at feed or rapid traverse rate respectively, said irreversible drive mechanisms serving to prevent rotation of said nut by said screw or vice versa. 7

2. In a machine tool, a movably mounted spindle supporting head, a spindle rotatably mounted in said head, a screw and nut mechanism operatively arranged to effect movement of said head, a motor carried by said head, power transmitting means operatively connecting said motor to said spindle to rotate it, irreversible driving means operatively connecting said motor to one element of said screw and nut mechanism for effecting movement of said head in synchronism With rotation of said spindle, a separate motor for efiecting movement of said head at rapid traverse rate, and another irreversible driving means operatively connecting said rapid traverse motor to another element of said screw and nut mechanism.

3. In a machine tool, a base, a table slidably mounted on said base, a headstock slidably mounted on said base, a detachable spindle head attached to said headstock, a plurality of spindles operably mounted in said head, a motor driven transmission operably disposed in said headstock and connected to drive said spindles, a speed selection mechanism connected with said transmission to provide a selective range of speeds for said spindles, a second transmission driven from said first-named transmission, a nut operably mounted in said headstock and driven from said second transmission, a screw mounted in said base to receive said nut, and a feed selection mechanism connected with said second transmission to provide a wide range of feed rates for said headstock directly proportional to the speed ra of said spindles.

4. An electrical control circuit for automatically controlling the operation of a machine tool comprising a motor connected to efiect movement of a machine member, selectively at one of a plurality of feed rates, a second motor connected to effect a machine member movement at a fixed feed rate, a power source connected to energize said motors, a control circuit connected to selectively control the energization of said motors, a timing relay in said circuit selectively operable to disconnect said first-mentioned motor after a predetermined time interval and another timing relay in said circuit selectively operable to disconnect said first-mentioned motor after a predetermined time interval and to connect said second motor to said power source.

5. An electrical machine tool control system comprising a movable machine element, a motor connected to drive said movable machine element, a second motor connected to drive said element, an electric control circuit operably disposed to selectively energize said motors to effect a desired operating cycle, a timing relay in said circuit disposed to disconnect said firstmentioned motor after a predetermined time interval at a selected point in the operating cycle, a second timing relay in said circuit disposed to disconnect said first-mentioned motor after a predetermined time interval and to connect said second motor to efiect movement of said machine element, and a switch in said circuit operable to select the one or the other of said timing relays.

6. An electrical control system for a machine tool having a base, a work retaining table slidably mounted on said base, a headstock including an interchangeable tool retaining spindle attachment slidably mounted on said base, a screw and nut drive mechanism operably connected to drive said headstock, and comprising a motor connected to, drive said mechanism at feed rate, a second motor connected to drive said mechanism at rapid traverse rate, a plurality of adjustable switches operably engageable at predetermined positions of headstock movement, an electric brake associated with said second motor and disposed to brake rapid traverse movement of said headstock, an electrical control circuit interconnecting said switches, motors and electric brake, a timing relay in said electrical control system operative to render said first mentioned motor inoperative, a second timing relay in said system operative to render said first-mentioned motor inoperative and to render said second motor operative, and a switch arranged to select the one or the other of said timing relays for operation in said control system, whereby said motors and brake may be sequentially energized to effect an operating cycle for said headstock as predeterminately selected through the adjustment of said switches.

7. In a machine tool, a base, a table slidably mounted on said base, a power driven headstock including an interchangeable. tool retaining spindle attachment slidably retained on said base, a motor connected to drive said headstock at feed rate, a second motor connected to drive said headstock at rapid traverse rate, a plurality of adjustable switches disposed to be operatively engaged at predetermined positions of headstock travel, an electrical control circuit interconnecting said motors and said switches and disposed to energize said motors and efiect a desired operating cycle, a timing relay in said circuit operative to disconnect said first-mentioned motor after a predetermined time interval in the operating cycle, a second timing relay in said circuit operative to disconnect said first-mentioned motor and toconnect said second-named motor to drive said headstock at rapid traverse rate, and a switch in said circuit operative to select the one or the other of said timing relays for controlling said headstock, whereby the operating cycle is readily varied for a particular machining operation by predeterminately setting said electrical control system.

JOSEPH B. ARMITAGE. JOHN B. LUKEY. KURT A. RIEDEL. FRANCIS D. BOEHMER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,796,332 Johnson Mar. 17, 1931 2,023,841 Kingsbury Dec. 10, 1935 2,029,335 Oberhoffken et a1. Feb. 4, 1936 2,040,872 Oberhoffken May 19, 1936 2,054,760 Oberhoffken Sept. 15, 1936 2,251,863 Young Aug. 5, 1941 2,333,341 Scrivener Nov. 2, 1943 2,387,820 Armitage et a1 Oct. 30, 1945 2,398,346 Anderson Apr. 16, 1946 

